Lock pin with pushbutton-operated axial locking and free bearing

ABSTRACT

A lock pin with pushbutton-operated axial locking has two locking elements which point in opposite directions and are mounted in radially outwards directed recesses in the body. To ensure a good, wear-resistant pivotal mounting of the two locking elements, combined with good locking action and resistance to shearing, the invention provides that the locking elements create a virtual, freely guided pivoting axis in their connection zone. The result is a pinless mounting of the locking elements.

The subject-matter of the invention is a lock pin withpushbutton-operated axial locking according to the introductory part ofclaim 1. Lock pins of this type are used as machine elements. The pinpart is inserted through a seat in a machine part so that it transfixestwo machine parts possessing a common aligned bore. Pushbutton-operatedspring-loaded locking elements are arranged at the forward free end ofthe pin part.

DE 10154692.0-24 originating from the same applicant, and constituting aprior right, describes a lock pin with pushbutton-operated axial lockingaccording to the introductory part of claim 1 wherein the lockingelements are configured as catches. The same document also showed thatthe locking element can have a film hinge, provided that it is made fromplastic material. Here, however, there are conflicting objectives, sinceon the one hand the material needs to be sufficiently flexible to form aserviceable film hinge, and on the other hand the locking elements needto have sufficient mechanical strength not to shear off while in lockingengagement.

Known from the unrelated field of hinged dowels are shaft-mountedpivotable locking elements which are initially passed through a hole ina wall-opening in the folded-down position and are then deployed andpivoted into the locking position by means of a screw thread.

Such hinged dowels, however, are not suitable for the repeated operationrequired in the context of machine parts. In particular, they are notdesigned for fatigue loading, as the locking position usually has to beprovided only once.

Incidentally, these unrelated catches lock in only one direction, whilstin the other direction, they are retractable.

Therefore the problem which lies at the basis of the invention is todevelop a lock pin with pushbutton-operated axial locking of the kindstated at the outset so that it can be used repeatedly for machineelements, and is able to sustain high breaking loads and shear forces.

For the solution to this problem, the invention is characterized by thetechnical teaching of claim 1. The essential feature of the invention isthat the locking elements according to the invention have a rigid,rather than a flexible, design, and the hinge axis is designed as avirtual bearing-axis. Therefore a hinge pin that could become worn oreven break under repeated flexing is no longer needed.

In a first preferred embodiment, the end of the pushrod forms a bearingshaft, while the catches themselves form bearing shells with asemi-circular configuration. This engineering design has provedeffective. Nevertheless assembly is difficult where such a lockingelement is intended for use in through bores of less than 6 mm diameter.In another configuration of the present invention, the bearing of thecatch is shifted outwards to a plunger that has a semi-circular slot inwhich lobes, shaped as quadrants, of the two catches are carried.

Instead of the configuration shown, i.e. a lobe, the bearing of thecatches may also be provided as a rib configured as a quadrant andextending over the full width.

In a third variant of the invention, the pushrod has an approximatelyrectangular recess in which the two catches are mounted. In this casethe catches have separate, slightly outwards-displaced bearing-axes.

The recess can of course be located on the opposite side, e.g. byconfiguring accordingly a spring plunger like the one used in the secondembodiment.

A further feature is that the pushrod is steadied on the other side bybeing “guided” in the above-mentioned spring-loaded plunger. At the sametime, by resting on this plunger, the bearing-axes of the catches have abetter mounting, that is to say, they are supported on both sides.

The pushrod may be guided in the plunger by a slot or an annular groove,or simply by guiding the pushrod externally or internally on theabove-described recess.

The invention will now be described in detail with the aid of a drawingshowing just one way of carrying out the invention. Further essentialfeatures and advantages of the invention will follow from the drawingand from its description.

In the drawings:

FIG. 1 shows a section through a first embodiment of a lock pinaccording to the invention in the locked condition,

FIG. 2 shows the view of FIG. 1 in the unlocked condition,

FIG. 3 is a perspective view of a locking element,

FIG. 4 shows a section through a second embodiment of a lock pin in thelocked condition,

FIG. 5 shows the view of FIG. 4 in the unlocked condition,

FIG. 6 shows an enlarged view as FIG. 4 but with spring omitted,

FIG. 7 shows an enlarged view as FIG. 5,

FIG. 8 is a perspective view of the locking element,

FIG. 9 shows a third embodiment of the invention, in section, in thelocked condition,

FIG. 10 shows the view of FIG. 9 in the unlocked condition,

FIG. 11 shows a modified form of the embodiment shown in FIG. 9,

FIG. 12 is a view from above of the embodiment of FIG. 11, with thelocking elements omitted,

FIG. 13 is a perspective side view of a locking element,

FIG. 14 shows a section through a fourth embodiment of a lock pin in thelocked condition,

FIG. 15 shows the view of FIG. 14 in the unlocked condition,

FIG. 16 shows, in section and on an enlarged scale, a modified form ofthe embodiment shown in FIG. 14,

FIG. 17 is an end view of the pushrod,

FIG. 18 is a side view of the pushrod,

FIG. 19 is a perspective view of a locking element for use in FIGS. 14to 18.

The lock pin 1 shown in FIGS. 1 and 2 consists of an approximatelycylindrical or square body 4 in whose central recess a pushrod 8 islongitudinally displaceably guided. As FIGS. 4 and 5 show, the pushrod 8has at its upper end an operating button 23 which is displaceablerelative to a bearing block 44 fixed with respect to the body of thepin. A circumferential recess 18 into which a cap 17 is latched byinwards directed projections 16 is arranged at the free, lower end ofthe body 4.

It is also feasible to provide the cap 17 with a screwed connection tothe body 4, instead of the latched connection 16, 18.

The body 4 is extended downwards in the form of a bearing thimble 15.The circumferential recess 18 is located in this area.

A spring element 19 is contained interior 14 the bearing thimble 15.This spring element 19 bears at one end on the bottom of the cap 17 andat the other end on the underside of two locking elements 2, 3 whichpoint in opposite directions.

In the locked condition, each locking element 2, 3 sticks out of arecess 5. These recesses 5 are opposite each other and are approximatelyradially aligned.

According to the invention the bearing-axis of the two locking elements2, 3 is pinless. That is to say, as shown in FIG. 3, each lockingelement 2, 3 is configured as a one-sided bevel 7 which springs from anapproximately rectangular locking body 6 and on the forward, free end ofwhich, two claws 9, 10, approximately semi-circular in shape and spacedapart from each other, are formed.

A gap 11 is formed between the two claws; and the space between theclaws 9, 10 of one locking element 2 forms a bearing shell 22 for theopposite locking element 3 (not shown in the drawing), which engages bya single, likewise semi-circular, claw into the gap 11 between the claws9, 10 of the locking element 2.

Thus, the two locking elements 2, 3 fit together in the region of acommon bearing shell 22, so forming the said virtual hinge-axis 12.

As FIG. 1 shows, the pushrod 8 reaches into the two locking elements byits lower end, which is configured as a blade 13.

It can be seen from FIG. 1 how the claw 20 on the locking element 3engages in the gap 11 between the claws 9, 10 of the locking element 2.

Upon operation of the pushbutton 23, the pushrod 8 is pushed downagainst the spring element 19, and the two locking elements 2, 3 aretilted downwards in the recess 5, producing the unlocked position shownin FIG. 2.

FIG. 1 also shows the central recess 31 in the bearing thimble 15 inwhich the spring element 19 is mounted.

Instead of a helical compression spring, any other known stored-energydevice such as elastomer springs, leg springs or spiral springs can, ofcourse, be used.

Upon operation of the pushrod 8, the virtual bearing-axis between thetwo locking elements 2, 3 therefore undergoes an axial displacement inthe direction of the arrow 21 of FIG. 3.

Instead of forming the hinge-axis 12 by the interlocking claws 9, 10,20, FIGS. 4 to 7 show a different embodiment.

Here, as shown in FIGS. 4 to 8, the bearing-axis is defined by forming aguide web 27, approximately in the shape of a quadrant, on each lockingelement 32, 33.

Each locking element 32, 33 again consists of an approximatelyrectangular solid body, with a bevel 26 at its inner end. The bevel 26tapers to a stop fin 28 on the end face.

Both guide webs 27 of the locking elements 32, 33 engage in a guide slot29 in a bearing plunger 24, as shown in FIG. 6.

In FIGS. 6 and 7 the spring element 19 has been omitted in order tosimplify the drawing.

Nevertheless FIG. 6 shows that when the bearing plunger 24 is in theraised position it bears, by a radially outwards directed shoulder 25with increased diameter, on the underside of the locking elements 32, 33pointing radially in opposite directions.

Upon operation of the pushrod 8, the blade 13 of the pushrod 8 movesinto the gap between the two locking elements 32, 33 and strikes bothstop fins 28.

This causes the two locking elements 32, 33 to tilt in the recess 5concurrently with the axial downward displacement of the bearing plunger24, as shown in FIG. 7.

Thus in the lock pin 30 shown in FIGS. 4 to 8 the virtual pivot-bearingbetween the two locking elements 32, 33 is formed by a pivoting bearingof each guide web 27 in a guide slot 29 in a bearing plunger 24 that isaxially guided under spring loading.

It will be obvious that additional axial guidance of the bearing plunger24 can also be provided in the region of the recess 31.

Such axial guidance of the bearing plunger 24 can thus be provided inthe region of both the surrounding bearing thimble 15 and of the bearingshell 14.

The advantage of this arrangement is that it, too, provides a pinlesspivot-bearing between the locking elements 32, 33. This pivot-bearingtherefore works with little or no wear and can be rated for a highnumber of load cycles.

Although the guide web 27 of FIG. 8 on the underside of each lockingelement 32, 33 is relatively narrow, it can, in another embodiment, bemade wider. The width of the guide web can also be matched to that ofthe locking element 32, 33.

In the further embodiment shown in FIGS. 9 to 13, an approximatelyrectangular recess is formed at the lower end of the pushrod 8 betweentwo parallel, endwisely-arranged fork-extensions 38.

Somewhat pin-like, round-profiled bearing-axles 37, which are straddledby the fork-extensions 38, are arranged at the inward ends of the twolocking elements 34, 35.

The bearing-axles 37 press on the shoulder 25 of increased diameterwhich is joined to the spring-loaded axially displaceable bearingplunger 36.

Thus, when pressure is applied to the pushrod 8, the bearing plunger 36is displaced downwards into the region of the cap 17, against the forceof the spring element 19, and the two locking elements 34, 35 pivotinwards into the unlocked position.

Incidentally, FIG. 13 shows that the locking elements 34, 35 can haveslots 41 instead of being joined to bearing-axles 37.

The fork-extensions 38 of the pushrod 8 engage in these slots 41 so thathere, too, a virtual pivot-bearing of the locking elements 34, 35manifests itself.

The locking elements 34, 35 are thereby juxtaposed in the region oftheir bevels 26, as shown in FIG. 10.

As FIGS. 9 and 10 show, the bearing plunger 36 is guided axially, andprevented from skewing, in the bearing thimble 15 on the opposite sideto the pushrod 8. For this purpose the shoulder 25 of the bearingplunger 36 has radially outwards directed extensions 39 affording linearguidance on the bearing thimble 15.

The bearing-axes thereby created on the locking elements 34, 35 are thussupported in all directions.

In a modified embodiment shown in FIGS. 14 to 19, the fork-extensions 38described above with reference to FIG. 11 can also be axially extended,and can engage in seats 42 in the region of the spring-loadedaxially-guided bearing plunger 43. This provides trouble-free axiallongitudinal guidance of the bearing plunger 43 in the lock pin 40 shownin FIGS. 14 and 15.

In a similar embodiment to FIGS. 9 to 13, the fork-extensions 38 can inthis case too engage in slots 41 in the opposite-way locking elements34, 35, so replacing the bearing-axles 37 formed on the locking elements34, 35 as shown in FIG. 16. FIG. 19 illustrates this.

A feature common to all embodiments is that a pinless pivot-bearing ofthe locking elements 2, 3; 32, 33; 34, 35 is shown, and that the lockingelements, as rigid, rather than flexible, bodies, have an excellentlocking action combined with good resistance to shear forces.

DRAWING LEGEND

-   1 lock pin-   2 locking element-   3 locking element-   4 body-   5 recess-   6 locking body-   7 bevel-   8 pushrod-   9 claw-   10 claw-   11 gap-   12 pivot axis-   13 blade-   14 interior of bearing thimble-   15 bearing thimble-   16 projection-   17 cap-   18 recess-   19 spring element-   20 claw-   21 direction arrow-   22 bearing shell (of 2, 3)-   23 operating button-   24 bearing plunger-   25 shoulder-   26 bevel-   27 guide web-   28 stop web-   29 guide slot-   30 lock pin-   31 recess-   32 locking element-   33 locking element-   34 locking element-   35 locking element-   36 bearing plunger-   37 bearing-axle-   38 fork-extension-   39 extension-   40 lock pin-   41 slot-   42 seat-   bearing block

1-9. (canceled)
 10. Lock pin with push-button-operated axial locking,comprising: a tubular body having radially outwards directed recesses;an actuating plunger in said tubular body and axially displaceable underspring loading; locking elements pointing in opposite directions whichare mounted in said radially outwards directed recesses in the body andwhich are moved by pressure of said plunger, and wherein the lockingelements form a virtual, freely guided pivoting axis in a connectionzone.
 11. Lock pin according to claim 10, wherein the locking elementsare rigid, inflexible bodies.
 12. Lock pin according to claim 10,wherein the pivoting axle/shaft is freely guided between the lockingelements and comprises a bearing shell positioned between the lockingelements, into which the plunger engages.
 13. Lock pin according toclaim 10, wherein the freely guided pivoting axis is positioned betweenthe locking elements and is a bearing plunger displaceably guided underspring loading, in which the two locking elements pivotably engage, eachby a guide web.
 14. Lock pin according to claim 13, wherein the lockingelement consists of a block-shaped or rectangular body on the undersideof which the guide web, substantially in the shape of a quadrant, isformed which engages pivotably in a guide slot in the bearing plunger.15. Lock pin according to claim 13, wherein the bearing plunger has anaxial longitudinal guide in the lock pin.
 16. Lock pin according toclaim 10, wherein the bearing-axles of the locking elements are formedby substantially round pins formed on the inwards-facing ends of thelocking elements and pivotably engaging in recesses in the bearingplunger displaceable under spring loading.
 17. Lock pin according toclaim 10, wherein the bearing-axles of the locking elements are formedby substantially round pins positioned parallel and spaced apart on theforward, free end of the plunger and engaging pivotably in slots in theend faces of the locking elements.
 18. Lock pin withpush-button-operated axial locking, comprising: a tubular body havingradially outwards directed recesses; an actuating plunger in saidtubular body and axially displaceable under spring loading; lockingelements pointing in opposite directions which are mounted in saidradially outwards directed recesses in the body and which are moved bypressure of said plunger, wherein the locking elements form a virtual,freely guided pivoting axis in a connection zone and wherein the plungerhas on its forward, free end two parallel fork-extensions circumscribinga recess in which two bearing-axles of the locking elements arepivotably held.
 19. Lock pin according to claim 18, wherein thefork-extensions engage seats in the bearing plunger guided under springloading, and are thereby guided.